All of the following are necessary to calculate the customer lifetime value EXCEPT ________.

A) customer level operating profit per year
B) length of customer relationship
C) economies of scale
D) discount rate

Customer Level Operating Profit

Customer Level Operating Profit refers to the profit earned from a customer, after deducting operating expenses directly associated with serving that customer.

Length of Customer Relationship

The duration over which a business maintains a relationship with an individual customer, significant for understanding customer loyalty and value.

Economies of Scale

Economies of scale are cost advantages that businesses obtain due to scale of operation, with costs per unit of output decreasing with increasing scale.